In this paper，a novel fluorescent probe with D-π-A structure（,1,） was synthesized by a one-step reaction using 1，2，3，3-tetramethyl-3H-indolium iodide as an electron acceptor and indole as an electron donor for the detection of drug-induced viscosity changes in cells. The structure of the fluorescent probe was characterized by nuclear magnetic hydrogen spectroscopy（,1,H NMR），nuclear magnetic carbon spectroscopy（,13,C NMR） and electrospray ionization mass spectrometry（ESI-MS）. The optical properties of the probe and the feasibility of response viscosity（,η,） were measured by fluorescence spectroscopy. The probe was added to different ratios of water-glycerol system，the fluorescence intensity（,I,） of probe increased gradually with the increasing ratio of glycerol. When the ratio of glycerol was 90%，the fluorescence intensity of the probe was enhanced by about 100 times compared with the pure water system. The analysis using the Förster-Hoffmann equation showed a good linear relationship between lg,I, and lg,η,（,r,2, = 0.998 0），and the lowest detection limit of the probe for viscosity was 1.167 cP，indicating the probe has good sensitivity to viscosity response and has the potential for quantitative viscosity detection. The probe did not respond to other active molecules，and the fluorescence intensity was little affected by organic solvents with small viscosity，and only had a better response to glycerol with large viscosity，which fully indicates that the probe degree has an excellent specificity to viscosity. The fluorescence of the probe both in the aqueous solution and the water-glycerol（90%） solution did not change significantly after 60 min keeping at room temperature. The fluorescence intensities of the probe both in aqueous solution and the water-glycerol（90%） solution were almost unchanged in the pH range of 4.0-9.0，which indicated that the probe has good photostability and pH stability. The probe had a low effect on cell viability within the experimental range，indicating that the probe has good biocompatibility. In addition，only weak fluorescence was observed after HeLa cells were co-incubated with the probe solution for 30 min. In contrast，after the probe solution was co-incubated with HeLa cells which were stimulated with rotenone and carbonyl cyanide chlorophenylhydrazone（CCCP） for 30 min，a significant increase in cell fluorescence brightness could be observed，indicating that the probe can effectively detect changes in viscosity in the cell microenvironment. All the above results indicate that the probe has the advantages of good stability，specificity and biocompatibility as a viscosity-responsive probe，and has excellent potential for biological applications.